title: Arsonic acid-presenting superparamagnetic iron oxide for pH-responsive aggregation under slightly acidic conditions.
abstract: We report the synthesis and characterization of the arsonic acid-presenting superparamagnetic iron oxide (SPIO). We used arsonoacetic acid as the ligand for SPIOs in aqueous media. The surface modification of the SPIOs was accomplished via the ligand exchange from undecanoic acid to the carboxyl moiety of arsonoacetic acid. Consequently, the well-dispersed arsonic acid-presenting SPIOs in water were obtained. We found that the dispersion state of the arsonic acid-presenting SPIOs can be sharply regulated by pH changes in the biological significant region. The well dispersion state of the arsonic acid-presenting SPIOs can be maintained at the neutral pH region. In contrast, the arsonic acid-presenting SPIOs can sensitively form the aggregation below pH 6.1. Moreover, these dispersion states can be controlled reversibly by the pH alteration in the narrow region.
authors.affiliation: Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Minehara
authors.forename: Kensuke
authors.initials: K
authors.lastname: Naka
authors.forename: Kazuo
authors.initials: K
authors.lastname: Tanaka
authors.forename: Asako
authors.initials: A
authors.lastname: Narita
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Chujo
mesh_terms: D001152:Arsenicals / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D058185:Magnetite Nanoparticles / Q000737:chemistry*
chemical_list: D001152:Arsenicals; D058185:Magnetite Nanoparticles; C054806:arsonic acid